In the 1960s to 70s, the government, financial institutions, and major companies introduced a mainframe system to process various data required for enterprise activities. The mainframe system refers to a general purpose large-size computer which employs a center concentration method which connects a plurality of terminals to one computer to perform various jobs. For example, system/360 by IBM is an example of a mainframe system. Mainframe systems have been continuously developed while leading the computing industry of enterprises for almost thirty years since then. However, at the end of the 80s, distributed environments with an open system such as the Unix platform gathered strength and downsizing of open systems became a trend, in order to save system operating costs, so that the position of mainframe systems has been largely weakened.
Differently from a mainframe system, an open system does not depend on a closed technique or program of a specific company. But the interface thereof is open so that the open system is connected or transplanted to a different kind of computer. UNIX is an example of an open system. Recently, there has been an attempt to entirely reconstruct a mainframe system into an open system, which is dangerous and requires high cost, a lot of manpower, and time.
A rehosting solution is suggested as a new alternative method. Rehosting is a high IT system implementation strategy which converts an IT system, which is constructed and operated in a mainframe system environment, into an open environment without redeveloping an application, to be reused as it is. The rehosting may save initial cost and time for the entire redevelopment and fully utilize an existing resource, so that risk is minimized and other various positive effects may be expected.
In order to reuse job control language in a different encoding environment, a sort script needs to be converted, like EBCDIC used in a main frame system and ASCII used in an open system. Therefore, the sorting order may be different between the main frame and the open environment, so that when a field used as a sorting key is configured by a complex field, a study for a method for separating the fields to be sorted by an adaptive encoding is necessary.